The present invention relates to a wire-locked coupling apparatus and, more particularly, to a wire-locked B-nut for coupling pipes or conduit which contain fluid, wherein the B-nut is secured by a removable retaining device.
There are a wide variety of connectors which are used to couple different pipes or tubes together. Some known connectors rely on the use of solder to form a seal between the tube and the connector, particularly when fluid flows through the joined conduit. In many applications, however, the connector needs to be removed to disassemble the coupled tubes in order to clean the conduit or to access a component blocked by the coupled tubes. Hence, a seal such as solder creates several problems. For example, solder seal connectors are only suitable for use with conduit which contains fluid at relatively low pressure, and cannot be used in high pressure systems. Also, the solder seal is difficult to remove, and removal of the solder will usually destroy the connector and, possibly, the conduit.
One type of known connector uses a retaining or locking wire, insertable into a groove along the inside circumference of the connector, to secure the connector to the tube and take out the axial seating loads. When the wire is inserted in the connector, it disappears into the connector along the groove. Although this type of seal overcomes many of the problems associated with the solder seal, the connector is still destroyed when disassembly is required, as the connector must be cut to be removed.
In an effort to overcome this problem, an alternative embodiment also discloses a composite structure of a wire and an attached end wherein the wire is insertable into a groove along the interior circumference of the connector the end protrudes from the connector after insertion of the wire into the connector. While it is intended that the protruding end can be grasped and pulled to remove the wire from the connector without destroying the connector, experience has shown that the end can become detached from the wire leaving the wire resident in the connector. Although this composite structure alternative overcomes some of the problems encountered by previous embodiments, a number of problems still exist. For example, the protruding end is formed separately from the wire, and then attached, creating a weak joint or stress concentration at the attachment. This weak joint can break during insertion or removal of the wire, causing separation of the protruding end from the wire and thereby making removal of the wire impossible without destroying the connector.
There thus exists a need for a connector seal which reduces the stress concentration at the interface between the protruding end and the wire, thereby reducing the possibility of the protruding end separating from the wire during wire removal.